The present invention concerns a sickleless internal gear pump having an internal ring gear and a pinion, and used for generating high pressure. A pump of this categorial design is known as a particular embodiment from DE 41 04 397 A1.
Internal gear pumps generally feature an internal ring gear with which an external pinion with a fewer number of teeth is in mesh, i.e., engages the ring gear in driving fashion. Normally, the teeth of such pumps--based on the diameter of the pinion or ring gear--are relatively narrow so that--once the volume flow to be pumped has been determined by the height of the teeth and the width of the gears--this volume flow is for design reasons limited with popular pumps. Sickleless internal gear pumps specifically have the advantage of a minimal size. For improving the tightness, viewed in peripheral direction, i.e., between the tooth heads of pinion and ring gear, DE 41 04 397 A1 already proposed to insert a sealing element in each of the tooth heads of one of the two gears. These sealing elements are on the backside in contact with the pressure region so that, as the gears mesh, they bear in sealing fashion on the tooth head of always the other gear.
On the sickleless internal gear pump known from DE 41 04 397 A1, however, due to manufacturing tolerances and/or as a consequence of current working conditions, that is, with unfavorable conditions between the rotating gearing parts of the ring gear and pinion, for one, and the fixed housing part for another, a gap may occur. A result of this gap is lacking tightness of the internal gear pump, which in the final analysis means a loss of medium pumped and thus a drop of the volumetric efficiency. The more favorable gap conditions required for a remedy could be realized only at an extremely high manufacturing expense.
The problem underlying the present invention is to propose a sickleless internal gear pump of the categorial type where the sealing effect in the pressure buildup between the opposing gearing parts, for one, and the housing part for another, is improved without causing the manufacturing expense to rise overproportionally, and with the result that the aforementioned shortcomings will be eliminated.